


Lusting For It

by FullOfBoredom



Category: Undertale (Video Game)
Genre: Breeding, Dacryphilia, Dubious Consent, Humiliation, Lustmare, M/M, Nightlust - Freeform, Restraints, Tentacle Sex
Language: English
Status: Completed
Published: 2021-01-24
Updated: 2021-01-24
Packaged: 2021-03-16 02:46:48
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,384
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28949148
Author URL: https://archiveofourown.org/users/FullOfBoredom/pseuds/FullOfBoredom
Summary: Lust is afraid of Nightmare.This is exactly what Nightmare wants.
Relationships: Sans/Sans (Undertale)
Comments: 3
Kudos: 64





	Lusting For It

Lust was afraid of Nightmare.

He’d been over to ‘the boys’ house. He knew how to deal with Horror, a little snack and a soft touch disarmed him. Killer needed an ego stroke and he’d come apart at the seams. Dust liked banter, even directly challenging boasts (if he was cautious), and as long as there wasn’t a weapon in hand or flaring magic, he was safe. Cross didn’t want anything to do with him, and when Red was around, he was about as normal as anyone not in league with the psychos club.

Nightmare was different though.

Lust lived his life feeling good and making other people feel good. It wasn’t all roses, but in general, he was full of good vibes. Nightmare lived his life spreading every bad emotion one could feel, and exacerbating the ones already there. He didn’t even have to try, he had a really bad aura, but he could, if tempted, really mess with your mind. 

“Hey.” Lust jumped. That had sounded so close to his ear, but Nightmare was all the way down the hall. He’d have felt him if he was closer.

“Hey Nightie! What’s happening?” Lust grinned so hard he could almost feel his cheeks crack. It was a habit to hide his nervousness under flirting, even if the person in question could see clean through it.

“Just wondering why you’re making yourself at home so often.” His eye looked unimpressed, tentacles softly slithering through the air around him.

“I’d hardly call my little visits ‘making myself at home.’ It’s not like I have a room, or even a drawer!” Lust laughed, waving dismissively at Nightmare, who was moving closer. Oh, that was fear crawling on his back.

“You’re disappointed by that. You’d have thought you’d get a formal invitation to one of those things by now.” 

“Well I don’t expect it, but I won’t deny it’s nice to be wanted.” Lust’s eyelights already shrunk to pinpricks. He blustered his way forward. “I mean, I don’t think anyone minds me being here but you. And once I find out what you like, you won’t mind either.”

Nightmare stood very close. He could kill him at this distance.

“And what makes you think you can find out anything about me?” His cyan eye locked in on Lust’s face. He could feel every single insecurity stand out in his mind, self-hatred rising followed quickly by shame. “You’d have better luck being interesting enough that I’d let you stay.”

“What do you wanna know?” Lust forced the casual smile. He’d put on this act a million times before, even if his breathing and eyes gave it away. “I’ll be so interesting, I’ll earn a drawer in your room.” He winked and prayed. He didn’t want a drawer in Nightmare’s room, but he DID want to play along.

Nightmare raised his eyebrow. 

“What are you afraid of, this instant?” Nightmare grinned lazily, a tentacle coming around to touch Lust’s face. It lightly stroked his cheek. Lust kept looking at his face.

“That you’ll kill me.” And Nightmare’s grin grew wider.

“Wrong.” Nightmare grabbed him with his tentacles, tightly wound around Lust’s limbs, carrying him into a place Lust had not been allowed in before now.

Nightmare’s room was dark, but elegant. Large armoire, large bed, patterned rug, all in dark browns and blacks and blues. It probably seldom saw use with its owner’s tendencies. Lust relaxed into the strange hold, breath racing while the soft tentacles undulated and tightened their hold; he could do nothing but wait for what Nightmare decided to do.

“You were afraid I’d find you interesting.” He placed Lust by the bed. He’d normally feel safer on one, but Nightmare’s aura was potent, focused. “Your mistake was challenging me. I’ll find out just how interesting you really are.” Nightmare kept his hands in his pockets; his tentacles did all the work of running over Lust’s body, but it thankfully didn’t escalate to taking clothes off.

“H-How do you plan on doing that?” Lust shivered, keeping his body loose. Locked joints would hurt if Nightmare suddenly pulled on them.

“Just gunna ask you some questions. Don’t mind the restraints, they just keep you from running away.” Nightmare smiled lazily, like this was some normal interrogation method he did with people. Lust grinned through the nerves.

“I do well in restraints.” Lust arched his hips. “What’s the safeword?” His performance was probably on par with his first real time with a client. Nightmare chuckled darkly.

“Who said this would be safe?” Lust felt a physical wave of dread seep in through his limbs. “Guess you’ll just have to trust me.” The next wave filled him with guilt. Nightmare waited until he could see it on Lust’s face, wracked with discomfort.

“Now, what’s on your mind?” Lust tried to look away, but Nightmare positioned him to make it impossible.

“That you probably don’t use these tentacles for fun, and that’s such a waste.” Nightmare’s tendrils started creeping closer to his clothes. He almost got a laugh.

“Come, now. It can’t all be innuendos in there.”

“It’s most of what I got.” Lust took a deep breath. “I’m also terrified of what you consider fun.”

“That’s still not your most pressing concern. What could you be hiding?…” Nightmare pushed out feelings of paranoia, concern, sadness. “I haven’t picked apart sexual secrets. At least this’ll be enlightening.” 

Lust held in a shaky breath and a sob. Nightmare’s powers were potent at this range, direct contact just making it worse. He sagged in Nightmare’s restraints.

“Why’re you doing this to me?” Lust cried, tears pooling up on his face. Nightmare followed the tear track all the way down. “I’m a bad person, but you’re worse.” Lust sobbed while Nightmare held him straight up, eye to eye with the bastard. Then he stuck out his cyan tongue and licked right up his cheek.

“I know I am. Your sorrow is delicious.” Lust looked shocked and appalled, but Nightmare repeated the action on the other one, groan rumbling in his black goopy body. “What’re you hiding?” He stared into Lust’s eyes from up close. “You know I can make you tell me. It’s just a matter of time.”

“I’m gunna make you work for it.” Lust growled at him, but Nightmare just cupped Lust’s face in his hands. The effect was so much more powerful with the increasing contact. Lust’s mind blanked out when Nightmare kissed him. The tongue worked its way inside, Lust kept getting angrier, fighting the tongue every inch it tried to explore. Lust struggled hard against the tentacles, trying to make Nightmare give up on trying to find out anymore about him. However, Nightmare pulled back humming to himself.

“You certainly do know how to make yourself tempting. That anger?” Nightmare’s hands traced his hips, his spine, his ribcage. “So sweet. Still not the right emotion though.” He licked up Lust’s angry tears again. 

Lust didn’t know how to feel anymore. Nightmare’s hold on his emotions strangled his brain, but his body knew the motions and, shamefully, was turned on by the prospect he was faced with. He liked new experiences, but being fucked by the embodiment of negativity really shouldn’t have made the list. He just felt more and more ashamed of himself, face bright pink and upset, before he realized what was happening.

“Caught on? Good.”

Nightmare went to undo Lust’s bottoms, letting them slide off, moving the tentacles over them until they fell off. Lust tried to move his knees together, but Nightmare wasn’t having it.

“Tell me what you’re hiding.” Lust’s arms were hoisted above his head, so that one tentacle could hold both. His legs were forcibly spread by one restraint each, which freed up one to…

Oh god.

“Okay, you caught me, the thought of those tentacles isn’t new to me, but have you ever done this before? What is that gunna do to me???” Nightmare looked up at his face.

“No idea. Maybe you should confess before we find out.” The tip teased against his entrance and Lust could feel how odd the goopy texture was. It slid back and forth along his slit, which was embarrassingly wet with the white hot shame creeping into every bone.

“I did!” It pushed the very tip in. “I told you I wanted this! With you, with the tentacles, I spilled!” Lust arched his hips to try to get away, but the tentacle was flexible and couldn’t be escaped. It pressed into him, slowly, and Lust cried out. Tears burned down his cheeks and his soul filled with the most intense shame he’d ever felt. He could feel the cyan tongue tracing over his cheeks again. He felt the intrusion sink farther and farther until it hit the back of his pussy. He moaned with the undulation inside, thicker and thinner and wiggling around in there.

“There’s something deeper than that. Something you’ve been hiding a long time.” The tentacle thrusted experimentally. Lust shrieked, tightening around it. Nightmare still hadn’t switched from a lazy smile. “I’ll keep you here as long as it takes.” It thrust slowly, keeping Lust at a pace where he could never peak, only cry in frustration.

“Hnnnnnnnnnnngh.” The tentacle touched every inch inside him. Well almost every inch.

Lust struggled to think through the shame and embarrassment at being such an easy mark, Nightmare hadn’t even wanted to have him and Lust still tempted him into it. He was a dirty slut, a sex obsessed skeleton, and while he had a lot of unsavory desires one shouldn’t mention in polite company, he had one that was pretty taboo for his profession.

Nightmare stared expectantly, sensing the peak of Lust’s resignation. He had buried this little desire away so hard that it didn’t occur to him that this is what Nightmare wanted until now.

“Well?”

“I wanna be knocked up.” Lust cried and cried, squeezing his eyes shut at the thought of having to say this out loud. “I want someone to cum inside me without protection and I get knocked up with their souling.” Lust twisted around the writhing tentacle, that was slowly picking up speed while he kept sobbing. “I want to be full of my partner’s cum and let it grow inside me, carry all the children they could ever want, use my body over and over again!” He felt a tongue in his mouth that prevented him from speaking further. Nightmare had a wide excited eye when he pulled back.

“Now _that’s_ interesting.” 

Nightmare slid the tentacle out of him, laughing at Lust’s whine. He removed his shorts, and pulled those hips towards him. Then he positioned the sopping wet tentacle right in front of Lust’s face.

“Well now that you’ve told me, I guess I can indulge your little fantasy.” He pulled Lust right onto his glowing cyan cock, forcing the tentacle into Lust’s mouth when he cried out.

Lust couldn’t do anything but ride the wave. Shame ate at his soul, but he still took on the task of tending to the tentacle. It tasted like his own pussy and that was familiar ( _the shame_ ) enough to anchor himself in the moment. Still held up by his arms, legs held apart, sucking on the fourth tentacle, and positioned right onto Nightmare’s cock. His unprotected cock, that was fucking his unprotected pussy, readying up to blow a nice load of hot magic right into his body.

Part of him panicked so hard. This was _Nightmare_ and he didn’t want a baby with the psycho! But so much was being overridden by the fact that he was being _bred like a good little bitch_.

“Thinking about being a breeding slut?” Nightmare thrust into him rhythmically. “You could just spend your days in the house, taking turns getting knocked up by all of us. Always let you walk around with a little souling or two growing in your body.” The tentacle started leaking black liquid down Lust’s throat. “How many do you think your little body could contain? There _are_ six of us after all…” Lust whimpered hard around the tentacle half thrusting into his throat, moaning with reckless abandon with tears still streaming down his face. His pussy got tighter around Nightmare until he came with a growl.

Lust felt his body filling with hot cum and LOST IT.

He half gagged on the black goop pouring down his throat, settling in his body while Nightmare filled his pussy with cum. He didn’t stop convulsing until Nightmare removed the restraints and pulled out of him. Still overcome with shame, he used his fingers to prevent any from slipping out of his hole.

Lust laid back on the bed, fingers keeping him from spilling, just trying to catch his breath. He felt wrung out like a towel, the effect of so much emotion manipulation exhausting him. The other part of him wanted to enjoy the moment. He didn’t do this very often, and savoring it was a priority since it couldn’t be undone.

Nightmare was already dressed, but looked over the wrecked Lust still on his bed. Without a word, he pulled Lust’s fingers out and pushed a tentacle in.

Lust wiggled but didn’t resist, even when the pressure turned to pain. When Nightmare pulled it out, Lust went to prevent any spilling again, but found nothing there. He glanced down at his body. He found a large pocket of magic deep in his body, where his womb was, but stretched out significantly.

“I’m going out to cause some chaos. Just close the door on the way out.” Nightmare tossed him his pants and walked towards the door. “The room next to Horror’s is empty. Do with that what you will.”

Lust found himself staring at the black monster as he opened the door and walked out, but before Lust even got his pants on, Nightmare popped his head back in again.

“Also, most of the guys are home, and well…” He glanced pointedly at Lust’s midsection. “ _You’ve got a lot of room_.” And this time he really did go, leaving Lust with that thought and a bright pink face.

He walked into the living room, a lot more lively.

“Hey boys. I want your help with something…”

**Author's Note:**

> Written as part of Kinktober.


End file.
